BACKGROUND
Technical Field
[0001] The present invention relates to a curable composition, an accommodating unit, a
device for forming a two or three dimensional image, a method of forming a two or
three dimensional image, and cured matter.
Description of the Related Art
[0002] Active energy ray curable inks are used or supplied for offset, silk screen, top
coating agents, etc. and become popular due to its cost reduction by simplifying drying
processes and advantages such as less volatile amounts of solvents, which is good
for protection of the environment. For example, decorative printing on a substrate
with an active energy ray curable ink is expanding for industrial use.
[0003] However, for designing an active energy ray-curable ink required to be clear and
transparent in the case of a transparent ink or have a high level of whiteness in
the case of a white ink, active energy ray curable inks have been tried to improve
the tendency of the active energy ray curable ink changing color into yellow upon
application of active energy rays.
[0004] For example, an ink composition containing at least a polymerizable compound, a photopolymerization
initiator, a polymerization accelerator, and a fluorescent whitener has been proposed
in which the absorption wavelength band of the photopolymerization initiator and the
emission wavelength band of the fluorescent whitener partially overlap (for example,
in
JP-2006-274025-A1).
SUMMARY
[0005] According to embodiments of the present disclosure, a curable composition can be
provided which strikes a balance between excellent hue and excellent storage stability
while securing a high level of curability and good discharging stability.
[0006] According to embodiments of the present disclosure, provided is a curable composition
which contains a polymerizable compound, a polymerization initiator, and a fluorescent
whitener containing a benzoxazole derivative, wherein the proportion of the fluorescent
whitener is from 0.10 to 0.3 percent by mass and the proportion of the polymerization
initiator is from 5 to 15 percent by mass.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] Various other objects, features and attendant advantages of the present invention
will be more fully appreciated as the same becomes better understood from the detailed
description when considered in connection with the accompanying drawings in which
like reference characters designate like corresponding parts throughout and wherein:
FIG. 1 is a schematic diagram illustrating an example of an image forming device equipped
with an inkjet discharging device;
FIG. 2 is a schematic diagram illustrating an example of another image forming device
(device for fabricating a three-dimensional image); and
FIGS. 3A, 3B, 3C, and 3D are schematic explanatory diagrams illustrating an example
of a method of solid free-form fabrication using a curable composition.
[0008] The accompanying drawings are intended to depict example embodiments of the present
invention and should not be interpreted to limit the scope thereof. The accompanying
drawings are not to be considered as drawn to scale unless explicitly noted. Also,
identical or similar reference numerals designate identical or similar components
throughout the several views.
DESCRIPTION OF THE EMBODIMENTS
[0009] In describing embodiments illustrated in the drawings, specific terminology is employed
for the sake of clarity. However, the disclosure of this specification is not intended
to be limited to the specific terminology so selected and it is to be understood that
each specific element includes all technical equivalents that have a similar function,
operate in a similar manner, and achieve a similar result.
[0010] As used herein, the singular forms "a", "an", and "the" are intended to include the
plural forms as well, unless the context clearly indicates otherwise.
[0011] Moreover, image forming, recording, printing, modeling, etc., in the present disclosure
represent the same meaning, unless otherwise specified.
[0012] Embodiments of the present invention are described in detail below with reference
to accompanying drawing(s). In describing embodiments illustrated in the drawing(s),
specific terminology is employed for the sake of clarity. However, the disclosure
of this patent specification is not intended to be limited to the specific terminology
so selected, and it is to be understood that each specific element includes all technical
equivalents that have a similar function, operate in a similar manner, and achieve
a similar result.
[0013] For the sake of simplicity, the same reference number will be given to identical
constituent elements such as parts and materials having the same functions and redundant
descriptions thereof omitted unless otherwise stated.
Curable Composition
[0014] The curable composition of the present disclosure includes a polymerizable compound,
a polymerization initiator, and a fluorescent whitener containing a benzoxazole derivative,
wherein the proportion of the fluorescent whitener is from 0.10 to 0.3 percent by
mass and the proportion of the polymerization initiator is from 5 to 15 percent by
mass. The curable composition may furthermore optionally contain other components.
[0015] Fluorescent whiteners absorb light in the ultraviolet region of a wavelength of from
200 to 400 nm and emits fluorescence in the visible region of a wavelength of from
400 to 600 nm. Therefore, if such a fluorescent whitener is used in combination with
a pohtopolymerization initiator, light absorption of the photopolymerization initiator
and the fluorescent whitener compete with each other, which inevitably degrades curability
of an active energy ray curable ink. In addition, since polymerization accelerators
are fine particle having a polymerizable functional group and an amino group on the
surface, there is a concern about degradation of discharging stability and a decrease
in gloss and a decrease in color gamut due to unevenness of the surface.
[0016] On the other hand, in the curable composition of the present disclosure, the fluorescent
whitener contains a benzoxazole derivative, the proportion of the fluorescent whitener
is from 0.10 to 0.3 percent by mass, and the proportion of the polymerization initiator
is from 5 to 15 percent by mass. This strikes a balance between excellent hue and
excellent storage stability while securing a high level of curability and good discharging
stability.
[0017] As the curable composition of the present disclosure, a curable clear ink composition,
a thermocurable composition, an active energy ray curable composition, etc., can be
used. Of these, the active energy ray curable composition is more suitable.
Polymerizable Compound
[0018] Examples of the polymerizable compound include, but are not limited to, a monofunctional
monomer, a polyfunctional monomer, and a polymerizable oligomer.
Monofunctional Monomer
[0019] The monofunctional monomer is not particularly limited and can be suitably selected
to suit to a particular application.
[0020] Specific examples include, but are not limited to, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl
(meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl
(meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isooctyl (meth)acrylate,
2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl
(meth)acrylate, 3-methoxybutyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl
(meth)acrylate, ethoxydiethylene glycol (meth)acrylate, 2-hydroxyethyl (meth)acrylate,
ethyl diglycol (meth)acrylate, cyclic trimethylolpropane formal mono(meth)acrylate,
imide (meth)acrylate, isoamyl (meth)acrylate,ethoxylated succinic acid (meth)acrylate,
trifluoroethyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, benzyl
(meth)acrylate, methylphenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl
(meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, tribromophenyl
(meth)acrylate, ethoxylated tribromophenyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate,
(meth)acryloyl morpholine, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl
(meth)acrylate, 1,4-cyclohexanedimethano mono(meth)acrylate, 2-(2-ethoxyethoxy) ethyl
(meth)acrylate, stearyl (meth)acrylate, diethylene glycol monobutyl ether (meth)acrylate,lauryl
(meth)acrylate, isodecyl (meth)acrylate, 3,3,5-trimethylcyclohexanol (meth)acrylate,
isooctyl (meth)acrylate, octyl/decyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone
(meth)acrylate, ethoxylated (4) nonylphenol (meth)acrylate, methoxypolyethylene glycol
(350) mono(meth)acrylate, methoxypolyethylene glycol (550) mono(meth)acrylate, N-vinylformamide,
N-vinylcaprolactam, and vinylpyrrolidone. These can be used alone or in combination.
Of these, isobornyl (meth)acrylate, (meth)acryloyl morpholine, cyclic trimethylolpropane
formal (meth)acrylate, and hydroxyethyl (meth)acrylate are preferable.
[0021] The proportion of the monofunctional monomer to the total mass of the curable composition
is preferably from 50 to 90 percent by mass and more preferably from 70 to 90 percent
by mass.
Polyfunctional Monomer
[0022] The polyfunctional monomer has two or more ethylenically unsaturated double bonds.
[0023] Specific examples include, but are not limited to, tricyclododecane dimethylol di(meth)acrylate,
hexamethylene di(meth)acrylate, trimethylol propane tri(meth)acrylate, pentaerythritol
tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate,
polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene
glycol di(meth)acrylate, tripropylene glycol tri(meth)acrylate, polypropylene glycol
di(meth)acrylate, neopentyl glycol di(meth)acrylate, bispentaerythritol hexa(meth)acrylate,
diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethoxylated 1,6-hexanediol
di(meth)acryle, 1,4-butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate,
2-n-butyl-2-ethyl-1,3-propanediol di (meth)acrylate, neopentyl glycol di(meth)acrylate
hydroxypivalate, trimethylolpropane tri(meth)acrylate hydroxypivalate, 1,3-butylene
glycol di(meth)acrylate, ethoxylated tri(meth)acrylate phosphate, ethoxylated tripropylene
glycol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate,
stearic acid-modified pentaerythritol di(meth)acrylate, tetramethylolmethane tri(meth)acrylate,
tetramethylol methane tetra(meth)acrylate, tetramethylol propane tri(meth)acrylate,
caprolactone-modified trimethylolpropane tri(meth)acrylate, propoxylate glyceryl tri(meth)acrylate,
ditrimethylol propane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate,
dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate,
dipentaerythritol hydroxypenta (meth)acrylate, neopentyl glycol oligo(meth)acrylate,
1,4-butanediol oligo(meth)acrylate, 1,6-hexanediol oligo(meth)acrylate, trimethylolpropane
oligo(meth)acrylate, pentaerythritol oligo(meth)acrylate, ethoxylated neopentyl glycol
di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol
di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, and propoxylated
trimethylolpropane tri(meth)acrylate. These can be used alone or in combination.
[0024] The proportion of the polyfunctional monomer including the polyfunctional polymerizable
oligomer, which is described later, is preferably from 0.01 to 20 percent by mass
and more preferably from 5 to 15 percent by mass to the total content of the curable
composition.
Polymerizable Oligomer
[0025] The polymerizable oligomer has an ethylenically unsaturated double bond. Examples
include, but are not limited to, an aromatic urethane oligomer, an aliphatic urethane
oligomer, an epoxy acrylate oligomer, a polyester acrylate oligomer, and other special
oligomers.
[0026] The polymerizable oligomer is available on the market. Specific examples include,
but are not limited to, UV-2000B, UV-2750B, UV-3000B, UV-3010B, UV-3200B, and UV-3300B,
UV-3700B, UV-6640B, UV-8630B, UV-7000B, UV-7610B, UV-1700B, UV-7630B, UV-6300B, UV-6640B,
UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7630B, UV-7640B, UV-7650B, UT-5449, and
UT-5454 (all manufactured by The Nippon Synthetic Chemical Industry Co., Ltd.), CN902,
CN902J75, CN929, CN940, CN944, CN944B85, CN959, CN961E75, CN961H81, CN962, CN963,
CN963A80, CN963B80, CN963E75, CN963E80, CN963J85, CN964, CN965, CN965A80, CN966, CN966A80,
CN966B85, CN966H90, CN966J75, CN968, CN969, CN970, CN970A60, CN970E60, CN971, CN971A80,
CN971J75, CN972, CN973, CN973A80, CN973H85, CN973J75, CN975, CN977, CN977C70, CN978,
CN980, CN981, CN981A75, CN981B88, CN982, CN982A75, CN982B88, CN982E75, CN983, CN984,
CN985, CN985B88, CN986, CN989, CN991, CN992, CN994, CN996, CN997, CN999, CN9001, CN9002,
CN9004, CN9005, CN9006, CN9007, CN9008, CN9009, CN9010, CN9011, CN9013, CN9018, CN9019,
CN9024, CN9025, CN9026, CN9028,CN9029, CN9030, CN9060, CN9165, CN9167, CN9178, CN9290,
CN9782, CN9783, CN9788, and CN9893 (all manufactured by Sartomer Company), EBECRYL210,
EBECRYL220, EBECRYL230, EBECRYL270, KRM8200, EBECRYL5129, EBECRYL8210, EBECRYL8301,
EBECRYL8804, EBECRYL8807, EBECRYL9260, KRM7735, KRM8296, KRM8452, EBECRYL4858, EBECRYL8402,
EBECRYL9270, EBECRYL8311, and EBECRYL8701 (all manufactured by Daicel Cytec). These
can be used alone or in combination.
[0027] The proportion of the polymerizable oligomer to the total mass of the curable composition
is preferably from 0.01 to 15 percent by mass and more preferably from 1 to 10 percent
by mass. When the proportion is from 0.01 to 15 percent by mass, a cured product with
good attachability and sufficient hardness can be obtained.
Polymerization Initiator
[0028] The composition of the present disclosure may contain a polymerization initiator.
In addition, the polymerization initiator is also simply referred to as an initiator.
Examples of the polymerization initiator include, but are not limited to, thermal
polymerization initiators and photopolymerization initiators.
[0029] The photopolymerization initiator produces active species such as a radical or a
cation upon an application of energy of active energy rays and initiates polymerization
of a polymerizable compound (monomer or oligomer). It is suitable to use a known radical
polymerization initiator, a cation polymerization initiator, a base producing agent,
or a combination thereof as the photopolymerization initiator. Of these, radical polymerization
initiators are preferable.
[0030] Specific examples of the radical polymerization initiators include, but are not limited
to, aromatic ketones, acylphosphineoxide compounds, aromatic oniumchlorides, organic
peroxides, thio compounds (thioxanthone compounds, compounds including thiophenyl
groups, etc.), hexaarylbiimidazole compounds, ketoxime-esterified compounds, borate
compounds, azinium compounds, metallocene compounds, active ester compounds, compounds
having a carbon halogen bond, and alkylamine compounds.
[0031] In addition, a polymerization accelerator (sensitizer) can be optionally used together
with the polymerization initiator. The polymerization accelerator is not particularly
limited. Specific examples include, but are not limited to, amine compounds such as
trimethyl amine, methyldimethanol amine, triethanol amine, p-diethylamino acetophenone,
p-dimethylamino ethylbenzoate, p-dimethyl amino benzoate-2-ethylhexyl, N,N-dimthyl
benzylamine, and 4,4'-bis(diethylamino)benzophenone.
[0032] The proportion of the polymerization accelerator is suitably determined to suit to
a particular application depending on the identification and the amount of the polymerization
initiator.
[0033] The proportion of the polymerization initiator to the total mass of the curable composition
is preferably from 5 to 15 percent by mass and more preferably from 7 to 12 percent
by mass. When the proportion of the polymerization initiator is 5 percent by mass
or more, the curability is good. When the proportion of the polymerization initiator
is 15 percent by mass or less, yellowing does not occur after curing.
[0034] The absolute difference (ΔHSP) between the Hansen solubility parameter (HSP) value
of the polymerizable compound and the HSP value of the polymerization initiator is
4 [(J/cm
3)
0.5] or less. When ΔHSP is 4 [(J/cm
3)
0.5] or less, the polymerization initiator can be easily dissolved, which ameliorates
the discharging stability.
[0035] The Hansen solubility parameter (HSP) is what is represented in a three dimensional
space using three components of dispersion term (δD), polarity term (δ), and hydrogen
bond term (δH), which are obtained by dividing the solubility parameter (SP) introduced
by Hidebrand. The dispersion term (δD) is based on proximity force of Van Der Waals.
The polarity (δP) is also referred to as polarization term and based on dipole moment
and dielectric constant. The hydrogen bond term (δH) includes an intermolecular force
based on hydrogen bond and furthermore other unclassifiable factors such as π-π interaction.
[0037] Hansen solubility parameters of many solvents and resins have been obtained, which
are described in, for example, Industrial Solvents Handbook, authored by Wesley L.
Archer.
[0038] The total HSP value is the sum of the three vectors described above. The HSP value
can be calculated by software such as HSPiP. Those having similar vectors based on
the HSP value can be determined to be highly compatible to each other.
[0039] The above-mentioned HSP value can be expressed as follows.
[0040] The factors in the relationship are as follows.
δD: Non-polar HSP value (dispersion HSP value)
δP: Polarity HSP value
δH: Hydrogen bond HSP value
Fluorescent Whitener
[0041] As the fluorescent whitener, benzoxazole derivatives are used.
[0042] A specific example is 1,4-bis(2-benzoxazolyl) naphthalene.
[0043] 1,4-bis(2-benzoxazolyl) naphthalene is represented by the following Chemical formula,
which can impart a bluish tint to a white or clear coating film and improves curability
as a sensitizer.
[0044] The benzoxazole derivative is available on the market. Specific examples include,
but are not limited to, Kayalight OS, Hostalux KCB, and Telalux KCB.
[0045] As the fluorescent whitener, in addition to the benzoxazole derivative mentioned
above, pyrene derivatives, coumarin derivatives, oxazole derivatives, thiazole derivatives,
imidazole derivatives, benzimidazole derivatives, imidazolone derivatives, pyrarizone
derivatives, benzidine derivatives, and stilbene derivatives can be used.
[0046] The fluorescent whitener is available on the market. Specific examples include, but
are not limited to, Hostalux KVC, KS, KS-N, KS-C, KSB, KSB-2, KCU, KM-N, NSM, SNR,
NR, N2R-200, and Leukopur EGM (all manufactured by Clariant AG), UVITEX OB, OB-C,
and OB-P (all manufactured by Ciba Japan K.K.), Kayalight B and OSN (both manufactured
by Nippon Kayaku Co., Ltd.), Hakkol P and OB (both manufactured by Showa Chemical
Industry Co., LTD.), Whitefluor B, PSN, HCS, PHR, and PCS (all manufactured by SUMIKA
COLOR CO., LTD.), and NIKKAFLUOR RP, 2R, SB, KB, EFS, OB, SC 200, and MC (all manufactured
by Nippon Chemical Works Co., Ltd.).
[0047] The proportion of the fluorescent whitener is from 0.10 to 0.3 percent by mass to
the total content of the curable composition. When the proportion of the fluorescent
whitener is 0.10 percent by mass or more, the addition effect of the fluorescent whitener
becomes sufficient. When the proportion of the fluorescent whitener is 0.3 percent
by mass or less, transparency and durability are good after curing.
Other Optional Components
[0048] The curable composition of the present disclosure may furthermore optionally include
other components. The other components are not particularly limited and can be suitably
selected to suit to a particular application. Examples include, but are not limited
to, coloring materials, organic solvents, surfactants, polymerization inhibitors,
leveling agents, defoaming agents, penetration-enhancing agents, wetting agents (humectants),
fixing agents, viscosity stabilizers, fungicide, preservatives, antioxidants, ultraviolet
absorbents, chelate agents, pH regulator, and thickeners.
Coloring Material
[0049] The curable composition may include a coloring material. However, it is preferable
that the curable composition be substantially free of the coloring material. The curable
composition of the present disclosure does not necessarily include a coloring material
and can be clear and colorless.
If the curable composition is free of a coloring material, the curable composition
is suitable as an overcoat layer to protect images.
As the coloring material, depending on the objectives and requisites of the composition
in the present disclosure, various types of pigments and dyes can be used to impart
black, white, magenta, cyan, yellow, green, orange, and gloss color such as gold and
silver.
[0050] The proportion of the coloring material is not particularly limited and determined
considering the desired color density, dispersibility of the coloring material in
the curable composition, etc. Preferably, the proportion of the coloring material
to the total content of the curable composition is from 0.1 to 20 percent by mass.
[0051] The pigment can be inorganic or organic and a combination thereof.
[0052] Specific examples of the inorganic pigments include, but are not limited to, carbon
blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black,
and channel black, iron oxides, and titanium oxides.
[0053] Specific examples of the organic pigments include, but are not limited to, azo pigments
such as insoluble azo pigments, condensed azo pigments, azo lakes, chelate azo pigments,
etc.), polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone
pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo
pigments, isoindolinone pigments, and quinofuranone pigments, dye chelates such as
basic dye type chelates, acid dye type chelates, dye lakes such as basic dye type
lake and acid dye type lake, nitro pigments, nitroso pigments, aniline black, and
daylight fluorescent pigments.
In addition, a dispersant is optionally added to enhance the dispersibility of a pigment.
The dispersant has no particular limit. For example, it is suitable to use a polymer
dispersant conventionally used to prepare a pigment dispersion.
[0054] The dyes include, for example, acidic dyes, direct dyes, reactive dyes, basic dyes,
and combinations thereof.
Organic Solvent
[0055] The curable composition of the present disclosure may include an organic solvent.
However, it is preferable that the composition be free of the organic solvent. The
composition free of an organic solvent, in particular a volatile organic solvent (compound)
(VOC), is preferable because it enhances safeness at which the composition is handled
so that pollution of the environment can be prevented. Incidentally, the organic solvent
represents a conventional non-reactive organic solvent, for example, ether, ketone,
xylene, ethylacetate, cyclohexanone, and toluene, which is clearly distinguished from
reactive monomers. Furthermore, "free of' an organic solvent means that no organic
solvent is substantially included. The proportion thereof is preferably less than
0.1 percent by mass.
[0056] For each component in the curable composition, low molecular weight components such
as a polymerizable monomer and a polymerization initiator can be identified by, for
example, gas chromatography mass spectrometry. The polymer component is dissolved
in a poor solvent such as methanol to precipitate for separation. The main skeleton
and the proportion of the content of the chlorine atom can be identified by infrared
spectroscopy or elemental analysis.
Preparation of Composition
[0057] The curable composition of the present disclosure can be prepared by using the components
mentioned above. The preparation devices and conditions are not particularly limited.
For example, the curable composition can be prepared by loading a polymerizable compound,
a pigment, a dispersant, etc., into a dispersing machine such as a ball mill, a kitty
mill, a disk mill, a pin mill, and a DYNO-MILL to prepare a pigment liquid dispersion
followed by mixing with a polymerizable compound, a polymerization initiator, a fluorescent
whitener, a polymerization inhibitor, and a surfactant.
Viscosity
[0058] The viscosity of the curable composition of the present disclosure has no particular
limit and it can be adjusted to suit to a particular application and device. For example,
if a discharging device that discharges the curable composition from nozzles is used,
the viscosity thereof is 60 mPa·s or less, preferably in the range of from 3 to 40
mPa·s, more preferably from 5 to 30 mPa·s, furthermore preferably from 5 to 15 mPa·s,
and particularly preferably from 6 to 12 mPa·s in the temperature range of from 20
to 65 degrees C, preferably at 25 degrees C.
[0059] In addition, it is particularly preferable to satisfy this viscosity range without
including the organic solvent mentioned above. Viscosity can be measured by a cone-and-plate
type rotary viscometer (VISCOMETER TVE-22L, manufactured by TOKI SANGYO CO., LTD.)
using a cone rotor (1°34' × R24) at a rotational frequency of 50 rpm with a setting
of the temperature of hemathermal circulating water in a range of from 20 to 65 degrees
C. VISCOMATE VM-150III can be used for the temperature control of the circulating
water.
Curing Device
[0060] The curing device to cure the curable composition of the present disclosure utilizes
curing upon application of heat or active energy rays. Curing upon application of
active energy rays is preferable.
[0061] The active energy rays for use in curing the curable composition are not particularly
limited as long as they can apply energy to conduct polymerization reaction of the
polymerizable components in the curable composition. Specific examples include, but
are not limited to, electron beams, α rays, β rays, γ rays, and X rays, in addition
to ultraviolet rays. A particularly high energy light source obviates the need for
a polymerization initiator to proceed polymerization reaction. In addition, in the
case of irradiation of ultraviolet rays, mercury-free is strongly demanded in terms
of protection of environment. Therefore, replacement with GaN-based ultraviolet light-emitting
devices is greatly preferred from industrial and environmental point of view. Furthermore,
ultraviolet ray light-emitting diode (UV-LED) and ultraviolet ray laser diode (UV-LD)
are preferable.
[0062] Small size, long working life, high efficiency, and high cost performance thereof
make such irradiation sources desirable as an ultraviolet light source. It is more
preferable to use a light-emitting diode emitting light having a wavelength of from
350 to 450 nm, in particular, 350nm to 400 nm.
Field of Application
[0063] The application field of the curable composition of the present disclosure is not
particularly limited. It can be applied to any field where the active energy ray curable
composition is used and suitably selected to suit to a particular application. For
example, the curable composition is used as a resin for processing, a paint, an adhesive,
an insulant, a releasing agent, a coating material, a sealing material, various types
of resists, and various types of optical materials.
[0064] Furthermore, the curable composition of the present disclosure can be used as an
ink to form two-dimensional texts, images, and designed coating film on various types
of substrates and in addition, a solid object forming material to form a three-dimensional
image (solid freeform fabrication object). This material for a solid freeform fabrication
can be used as a binder for powder particles for use in powder additive manufacturing
to conduct solid freeform fabrication by repeating curing and laminating powder layers.
Also, it can be used as a solid constituting material (modeling material) or supporting
member (supporting material) for use in additive manufacturing (stereolithography)
method as illustrated in FIG. 2 and FIGS. 3A to 3D. FIG. 2 is a diagram illustrating
a method of discharging the active energy ray curable composition of the present disclosure
to a particular area followed by curing upon irradiation of active energy rays to
form a layer and laminating the layers (detail of which is described later).
[0065] FIGS. 3A to 3D are diagrams illustrating a method of irradiating a pool (accommodating
unit) 1 of the active energy ray curable composition 5 of the present disclosure with
active energy rays 4 to form a cured layer 6 having a particular form on a movable
stage 3 and sequentially laminating the cured layer 6 so that a solid freeform fabrication
object is obtained.
[0066] A device for fabricating a three-dimensional (solid) object by the curable liquid
composition of the present disclosure can be a known device and is not particularly
limited. For example, the device includes an accommodating device, a supplying device,
and a discharging device (applying device) of the curable composition, an active energy
ray irradiator (curing device), etc.
[0067] In addition, the present disclosure includes cured matter obtained by causing the
curable liquid composition to cure and processed products obtained by processing structures
having the cured matter formed on a substrate. The cured matter or structure having
a sheet-like form or film-like form is subject to molding process such as hot drawing
and punching to obtain such a processed product. The processed product is preferably
used for, for example, gauges or operation panels of vehicles, office machines, electric
and electronic machines, and cameras, which requires surface-processing after decorating
the surface.
[0068] The substrate is not particularly limited. It can be suitably selected to suit to
a particular application. Examples are paper, fiber, threads, fabrics, leather, metal,
plastic, glass, wood, ceramics, or composite materials thereof. Of these, plastic
substrates are preferred in terms of processability.
Accommodating Unit
[0069] The accommodating unit of the present disclosure means a container containing the
curable composition of the present disclosure and is suitable for the applications
as described above. For example, if the curable composition of the present disclosure
is used for ink, the accommodating unit containing the ink can be used as an ink cartridge
or an ink bottle. Therefore, users can avoid direct contact with the ink during working
such as transfer or replacement of the ink, so that fingers and clothes are prevented
from getting dirty. Furthermore, commingling of foreign matter such as dust in the
ink can be prevented. In addition, the container can be of any size, any form, and
any material. For example, the container can be designed for any particular purpose
and usage. It is preferable to use a light blocking material to block the light or
cover a container with a light blocking sheet, etc.
Image Forming Method and Image Forming Device
[0070] The image forming method (method of forming a two or three dimensional image) of
the present disclosure may utilize active energy rays, heating, etc. The image forming
method of the present disclosure includes at least irradiating the curable composition
of the present disclosure with active energy rays to cure the curable composition.
The image forming device (device for forming a two or three dimensional image) of
the present disclosure includes an irradiator to irradiate the curable composition
of the present disclosure with active energy rays and an accommodating unit containing
the curable composition of the present disclosure. The accommodating unit may include
the container mentioned above. Furthermore, the method and the device may respectively
include discharging the curable composition of the present disclosure and a discharging
device (application device) to discharge the curable composition of the present disclosure.
The method of discharging the curable composition is not particularly limited. Examples
are a continuous spraying method and an on-demand method. The on-demand method includes
a piezo method, a thermal method, an electrostatic method, etc.
[0071] FIG. 1 is a diagram illustrating an image forming device 20 including an inkjet discharging
device. Printing units 23a, 23b, 23c, and 23d respectively having ink cartridges and
discharging heads for yellow, magenta, cyan, and black active energy ray curable inks
discharge the inks onto a recording medium 22 fed from a supplying roll 21. Thereafter,
light sources 24a, 24b, 24c, and 24d emit active energy rays to the inks to cure the
inks so that a color image is formed. Thereafter, a recording medium 22 is transferred
(conveyed) to a processing unit 25 and a printed matter reeling roll 26. Each of the
printing unit 23a, 23b, 23c, and 23d may include a heating assembly to liquidize the
ink at the ink discharging unit. Moreover, a mechanism may be optionally disposed
which cools down the recording medium to an ambient temperature in a contact or non-contact
manner. In addition, the inkjet recording method may be either of a serial method
of discharging an ink onto a recording medium by moving the head while the recording
medium intermittently moves in accordance with the width of a discharging head or
a line method of discharging an ink onto a recording medium from a discharging head
held at a fixed position while continuously moving the recording medium.
[0072] The recording medium 22 is not particularly limited.
[0073] Specific examples include, but are not limited to, paper, film, metal, or complex
materials thereof. The recording medium 22 takes a sheet-like form but is not limited
thereto. The image forming device may have a simplex printing configuration capable
of printing on one side of a recording medium or a duplex printing configuration capable
of printing on both sides thereof.
[0074] Optionally, multiple colors can be printed with no or faint active energy rays from
the light sources 24a, 24b, and 24c, followed by irradiation of the active energy
rays by the light source 24d. This saves energy and cost.
[0075] The recorded matter on which images are printed with the ink for use in the present
disclosure includes articles having images or texts on a plain surface of conventional
paper, resin film, etc. a rough surface, or a surface made of various materials such
as metal or ceramic. In addition, due to lamination of two dimensional images, it
is possible to form an image partially with solid feeling (images with two dimension
and three dimension) or a solid object.
[0076] FIG. 2 is a schematic diagram illustrating an example of the image forming device
(device for fabricating a three-dimensional image) relating to the present disclosure.
The image forming device 39 illustrated in FIG. 2 uses a head unit (movable in the
AB direction) in which inkjet heads are arranged to discharge a first curable composition
from a discharging head unit 30 for fabrication and discharge the first curable composition
from discharging head units 31 and 32 for support and irradiate the applied first
curable composition with active energy rays emitted from ultraviolet irradiators 33
and 34 to solidify to form a first fabrication layer. This operation is repeated according
to the number of laminations while moving a stage 38 movable up and down, thereby
laminating support layers and fabrication layers to manufacture a solid freeform fabrication
object 35 including a laminated support 36. Thereafter, a laminated support 36 is
removed, if desired. The reference numeral 37 represents a support substrate for a
fabrication object. Although there is only one of the discharging head unit 30 for
fabrication illustrated in FIG. 2, the device may have two or more discharging head
units 30.
[0077] Having generally described preferred embodiments of this disclosure, further understanding
can be obtained by reference to certain specific examples which are provided herein
for the purpose of illustration only and are not intended to be limiting. In the descriptions
in the following examples, the numbers represent weight ratios in parts, unless otherwise
specified.
EXAMPLES
[0078] Next, the present disclosure is described in detail with reference to Examples but
not limited thereto.
Examples 1 to 5 and Comparative Examples 1 to 8
[0079] Each of the materials shown in Tables 1 to 3 was sequentially added during stirring
and thereafter stirred for two hours to prepare curable compositions of Examples 1
to 5 and Comparative Examples 1 to 8.
[0080] Next, for each of the obtained curable compositions, curability, storage stability,
discharging stability, and hue were evaluated in the following manner.
Curability
[0081] Using a UV irradiator (LH6, manufactured by Fusion Systems Japan Co., Ltd.), the
test machine mentioned below discharged each curable composition onto the substrate
mentioned below to form a solid cured product. The cured product was irradiated in
the wavelength region corresponding to UV-A region (from 350 to 400 nm) changing the
cumulative amount of light step by step from 1,000 mJ/cm
2, 500 mJ/cm
2, 200 mJ/cm
2, 100 mJ/cm
2, 50 mJ/cm
2, 20 mJ/cm
2, to 10 mJ/cm
2. Whether the curable composition was cured was determined as cured when the curable
composition was not attached to a finger by a sensory evaluation by palpation. After
determined as cured, the cured matter was subject to the following evaluation. This
is the palpation of a bulk (solid) cured matter and was evaluated according to the
following three levels.
Curing Condition
[0082] The cumulative amount of light required for curing in each Example was from 700 to
4,000 mJ/cm
2.
Preparation of cured product: Discharging tester equipped with GEN4 head (manufactured
by Ricoh Printing Systems Co., Ltd.)
Cured product design: solid printing on the entire surface, thickness about 20µm Substrate:
polycarbonate film (PC) (manufactured by Mitsubishi Engineering-Plastics Corporation,
Iupilon 100FE2000 masking, thickness 100 µm)
Evaluation Criteria
[0083]
- A: Not sticky by finger touch
- B: Slightly sticky by finger touch but no trace of finger remained
- C: Trace of finger remained
Storage Stability
[0084] Each curable composition was placed in a polyethylene container and sealed and stored
at 70 degrees C for three weeks. Thereafter, the mean volume diameter, the surface
tension at 25 degrees C, and the viscosity at 25 degrees C of each curable composition
were measured before and after the storage. Based on the change ratio to the initial
physical properties, storage stability was evaluated according to the following evaluation
criteria. In addition, of the physical properties of mean volume diameter, surface
tension, and viscosity, the physical property having the maximum change ratio was
evaluated for each curable composition. The rating A and the above are practically
usable levels.
Mean Volume Diameter
[0085] The mean volume diameter of the curable composition was measured using a particle
size analyzer (Nanotrac Wave-UT151, manufactured by MicrotracBEL Corp.).
Surface Tension
[0086] The surface tension of the curable composition was measured by using AUTOMATIC SUPERFACE
TENSIONMETER CBVP-Z (manufactured by Kyowa Interface Science Co., LTD.) according
to Wilhelmy method. It was measured at 25 degrees C.
Viscosity
[0087] Viscosity of the curable compound was measured by a cone plate type rotatory viscometer
(VISCOMETER TVE-22L, manufactured by TOKI SANGYO CO., LTD.) using a cone rotor (1°34'
x R24) at a rate of rotation at 50 rpm and at 25 degrees C of hemathermal circulating
water.
Evaluation Criteria
[0088]
S: 10 percent or less
A: Greater than 10 percent to 30 percent
B: Over 30 percent
Discharging Stability
[0089] Using an inkjet discharging head GEN5 (nozzle diameter: 26 µm, manufactured by Ricoh
Printing Systems Co., Ltd.), the head was heated to 50 degrees C, decapped, and left
for 10 minutes. The discharging stability of the curable composition was evaluated
according to the following criteria. A predetermined dummy discharging was conducted
before the discharging evaluation.
Evaluation Criteria
[0090]
- A: No missing dots, no bending
- B: Partially bends or missing
- C: No discharging
Hue
[0091] A solid image was formed by discharging 30 pL per pixel with 300 dpi x 300 dpi to
form a 5 cm x 5cm solid image. After drying the solid image, the CIE L*a*b color coordinate
of the solid image was measured by spectrophotodensitometer (X-Rite 938, manufactured
by X-Rite Inc.) to evaluate chromaticity {(color value (b* value)} based on the following
evaluation criteria. The rating B and the above are practically usable.
Evaluation Criteria
[0092]
- A: b* ≦ 1.5
- B: 1.5 < b* ≦ 3.5
- C: 3.5 < b*
Table 1
|
|
Example |
|
HSP value [(J/cm3)0.5] |
1 |
2 |
3 |
4 |
5 |
Polymerizable compound |
a-1 |
24 |
89.7 |
|
|
|
|
a-2 |
23 |
|
|
94.6 |
|
|
a-3 |
19 |
|
|
|
84.5 |
|
a-4 |
17 |
|
89.6 |
|
|
84.6 |
Polymerization initiator |
b-1 |
23 |
|
10 |
5 |
|
8 |
b-2 |
22 |
10 |
|
|
15 |
7 |
Fluorescent whitener |
c-1 |
- |
|
|
|
|
0.2 |
c-2 |
- |
|
0.2 |
0.2 |
0.3 |
|
c-3 |
- |
0.1 |
|
|
|
|
c-4 |
- |
|
|
|
|
|
Polymerization inhibitor |
Methoquinone |
- |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
Total (percent by mass) |
100 |
100 |
100 |
100 |
100 |
ΔHSP [(J/cm3)0.5] |
2 |
6 |
0 |
3 |
5.5 |
Evaluation result |
Curability |
A |
A |
B |
A |
A |
Storage property |
A |
A |
A |
A |
A |
Discharging stability |
A |
B |
A |
B |
B |
Hue |
A |
A |
A |
B |
B |
Table 2
|
HSP value [(J/cm3)0.5] |
Comparative Example |
1 |
2 |
3 |
4 |
Polymerizable compound |
a-1 |
24 |
|
|
94.3 |
89.8 |
a-2 |
23 |
|
|
|
|
a-3 |
19 |
89.3 |
|
|
|
a-4 |
17 |
|
79.6 |
|
|
Polymerization initiator |
b-1 |
23 |
10 |
20 |
5 |
10 |
b-2 |
22 |
|
|
|
|
Fluorescent whitener |
c-1 |
- |
0.5 |
|
0.5 |
|
c-2 |
- |
|
|
|
|
c-3 |
- |
|
0.2 |
|
|
c-4 |
- |
|
|
|
|
Polymerization inhibitor |
Methoquinone |
- |
0.2 |
0.2 |
0.2 |
0.2 |
Total (percent by mass) |
100 |
100 |
100 |
100 |
ΔHSP [(J/cm3)0.5] |
4 |
6 |
1 |
1 |
Evaluation result |
Curability |
A |
A |
c |
A |
Storage property |
C |
C |
A |
A |
Discharging stability |
A |
C |
A |
A |
Hue |
A |
B |
A |
C |
Table 3
|
HSP value [(J/cm3)0.5] |
Comparative Example |
5 |
6 |
7 |
8 |
Polymerizable compound |
a-1 |
24 |
89.75 |
|
|
97.6 |
a-2 |
23 |
|
|
|
|
a-3 |
19 |
|
|
|
|
a-4 |
17 |
|
89.6 |
83.6 |
|
Polymerization initiator |
b-1 |
23 |
10 |
10 |
16 |
2 |
b-2 |
22 |
|
|
|
|
Fluorescent whitener |
c-1 |
- |
0.05 |
|
|
0.2 |
c-2 |
- |
|
|
|
|
c-3 |
- |
|
|
0.2 |
|
c-4 |
- |
|
0.2 |
|
|
Polymerization inhibitor |
Methoquinone |
- |
0.2 |
0.2 |
0.2 |
0.2 |
Total (percent by mass) |
100 |
100 |
100 |
100 |
ΔHSP [(J/cm3)0.5] |
1 |
6 |
6 |
1 |
Evaluation result |
Curability |
A |
A |
A |
C |
Storage property |
A |
C |
C |
A |
Discharging stability |
A |
C |
C |
A |
Hue |
C |
B |
B |
A |
[0093] Details of the materials used in Examples and Comparative Examples in Tables 1 to
3 are as follows.
Polymerizable Compound
[0094]
- a-1: Hydroxyethyl acrylate ("HEA", HSP value: 24 [(J/cm3)0.5], manufactured by Osaka Organic Chemical Industry Ltd.)
- a-2: Acryloyl morpholine ("ACMO", HSP value: 23 [(J/cm3)0.5], manufactured by KJ Chemicals Corporation)
- a-3: Cyclic trimethylolpropane formal acrylate ("CTFA", HSP value: 19 [(J/cm3)0.5], manufactured by Osaka Organic Chemical Industry Ltd.)
- a-4: Isobornyl acrylate ("IBXA", HSP value: 17 [(J/cm3)0.5], manufactured by Osaka Organic Chemical Industry Ltd.)
Photo Polymerization Initiator
[0095]
- b-1: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, "IRGACURE TPO", manufactured
by BASF Japan Ltd., HSP value: 23 [(J/cm3)0.5])
- b-2: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, "Irgacure 819", HSP value:
22 [(J/cm3)0.5], manufactured by BASF Japan Ltd.)
Fluorescent Whitener
[0096]
- c-1: "Kayalight OS", benzoxazole derivative, manufactured by Nippon Kayaku Co., Ltd.
- c-2: "Hostalux KCB", benzoxazole derivative, manufactured by Clariant AG
- c-3: "Tellux KCB", benzoxazole derivative, manufactured by Clariant AG
- c-4: "Hostalux KS-N", stilbene bisbenzoxazole derivative, manufactured by Clariant
AG Polymerization Inhibitor
- 4-methoxyphenol: Methoquinone (manufactured by Seiko Chemical Co., Ltd.)
[0097] Aspects of the present disclosure are, for example, as follows.
- 1. A curable composition includes a polymerizable compound, a polymerization initiator,
and a fluorescent whitener containing a benzoxazole derivative, wherein the proportion
of the fluorescent whitener is from 5 to 15 percent by mass and the proportion of
the polymerization initiator is from 0.10 to 0.3 percent by mass.
- 2. The curable composition according to 1 mentioned above, wherein the absolute difference
between the Hansen solubility parameter (HSP) value of the polymerizable compound
and the HSP value of the polymerization initiator is 4 [(J/cm3)0.5] or less.
- 3. The curable composition according to 1 or 2 mentioned above, wherein the fluorescent
whitener contains 1,4-bis(2-benzoxazolyl)naphthalene.
- 4. The curable compound according to any one of 1 to 3 mentioned above, wherein the
polymerizable compound contains at least one member selected from the group consisting
of isobornyl (meth)acrylate, (meth)acryloylmorpholine, cyclic trimethylolpropane formal
(meth)acrylate, and hydroxyethyl (meth)acrylate.
- 5. The curable composition according to any one of 1 to 4 mentioned above wherein
the polymerizable compound contains a monofunctional monomer and the proportion of
the monofunctional monomer is from 50 to 90 percent by mass to the total content of
the curable composition.
- 6. The curable composition according to any one of 1 to 5 mentioned above, further
contains a coloring material.
- 7. The curable composition according to any one of 1 to 6 mentioned above is a curable
clear ink composition containing substantially no coloring material.
- 8. The curable composition according to any one of 1 to 7 mentioned above, wherein
the curable composition is an active energy ray curable composition.
- 9. The curable composition according to any one of 1 to 8 mentioned above is for use
in inkjet method.
- 10. An accommodating unit includes a container containing the curable composition
of any one of 1 to 9 mentioned above.
- 11. A device for forming a two or three dimensional image includes
an accommodating unit configured accommodating the curable composition of any one
of 1 to 9 mentioned above,
an application device configured to apply the curable composition, and a curing device
configured to cure the curable composition.
- 12. The device according to 11 mentioned above, wherein the curing device includes
a light-emitting diode configured to emit light having a wavelength of from 350 to
450 nm.
- 13. A method of forming a two or three dimensional image includes applying the curable
composition of any one of 1 to 9 mentioned above and curing the curable composition.
- 14. The method according to 13 mentioned above, wherein the curing includes emitting
light having a wavelength of from 350 to 450 nm by a light-emitting diode light source.
- 15. Cured matter formed by using the curable composition of any one of 1 to 9 mentioned
above.
- 16. A processed product manufactured by processing the cured matter of 15 mentioned
above.
- 17. A decorated object having a substrate having a surface decorated with the processed
product of 16 mentioned above.
[0098] Numerous additional modifications and variations are possible in light of the above
teachings. It is therefore to be understood that, within the scope of the above teachings,
the present disclosure may be practiced otherwise than as specifically described herein.
With some embodiments having thus been described, it will be obvious that the same
may be varied in many ways. Such variations are not to be regarded as a departure
from the scope of the present disclosure and appended claims, and all such modifications
are intended to be included within the scope of the present disclosure and appended
claims.